Internet-connected TVs made up 21% of all television sales in 2010, according to a recently released report by NPD Group's DisplaySearch. Shipments are expected to more than double by 2014.

The only problem is hardly anyone is using them to surf the Internet. Just 45% of those who say they have an Internet-connected TV use that feature, NPD Group found.

"It's not something they're looking for, but it's there," said Paul Semenza, senior vice president of NPD Group's DisplaySearch. "It's being included more and more as a standard feature in high-end sets."

In other words, people are picking up Internet-connected TVs without knowing it or caring. It's kind of like buying a car with rain-sensing wipers.

It doesn't help that accessing the Internet on TV is a maddening experience. There are a bazillion different options, from Wal-Mart's (WMT, Fortune 500) Vudu to Hulu Plus-ready TVs, to, yes, Linux-based Nokia (NOK) MeeGo TVs.

None allow the user to just kick back and zone out like they want to.

Only 57% of those that use the Internet features said they found the experience on their connected TVs "satisfying."

The latest attempt, Google (GOOG, Fortune 500) TV, has been criticized so much for difficulty of use that Google reportedly pulled its new TVs from appearing at the annual Consumer Electronics Show next month.

Internet-connected set-top boxes have had some degree of success, including Apple (AAPL, Fortune 500) TV, which reached the 1 million sales milestone last week. But stand-alone connected TVs are expected to be a big part of the coming CES showcase.

"It has got to be easy in order to broaden adoption," Semenza said. "What's most crucial is that TVs automatically detect a wireless connection and quickly guide the user through the process."

For those that do use the features, 57% are using it to access Netflix, and 47% view videos on YouTube.